Recent improvements in smoking articles, such as cigarettes, include cigarettes of a type having a fuel component, a physically separate aerosol generator or substrate and a separate mouthpiece component. See, e.g., U.S. Pat. No. 4,714,082 assigned to the assignee of this invention. Apparatus and processes for mass producing such improved cigarette smoking articles are disclosed, for example, in U.S. patent application Ser. No. 089,502 filed Jul. 16, 1993 and U.S. patent application Ser. No. 856,239 filed Mar. 25, 1992, both assigned to the assignee of the present invention and the disclosures of which are incorporated herein by reference.
In the manufacture of such cigarettes, the fuel component includes an extruded carbonaceous fuel element which is circumscribed by a resilient insulating jacket, such as a mat or layer of glass fibers, and is then overwrapped with a cigarette paper or paper-like material and glued, e.g., with a cold adhesive seal, along a longitudinal seam, to form a continuous cylindrical fuel rod. The continuous overwrapped fuel rod may then be cut into shorter lengths to form fuel components suitable for processing, e.g., a six-up fuel rod having a length of about 72 mm.
The aforesaid U.S. patent application Ser. No. 856,239 describes one known process for mixing and extruding the continuous carbonaceous fuel rod, circumscribing the rod with a resilient glass fiber jacket or layer, overwrapping the rod with a paper overwrap and cutting the rod into predetermined lengths for subsequent cutting into fuel elements for individual smoking articles. In that process, the rod extrudate still has a relatively high moisture content in the range of about 30% to 40% by weight at the time it is circumscribed by the jacket and overwrapped with paper. It is to be understood that percentages of moisture content referred to hereinafter are intended to be wet weight percent unless otherwise stated. Drying is accomplished according to the described process while the extruded fuel rod is in situ in the overwrapped fuel component during subsequent processing so that no specific drying apparatus is used or required.
According to the aforesaid U.S. patent application Ser. No. 089,502, drying of the fuel element may be accomplished after the extruded fuel rod is overwrapped and cut into predetermined lengths or at other stages of the cigarette manufacturing process. Several possible drying apparatus are disclosed, including passive dryers such as a timed accumulator system, e.g., a Resy accumulator available from Korber & Co., AG, of Hamburg, Germany (hereinafter "Korber") or an S-90 accumulator available from G. D. Societe per Anzioni of Bologna, Italy (hereinafter "GD") or active dryers, such as a hot air blowing system. It is also suggested in that application that the drying stages may be eliminated and relocated since the moisture content of the extruded fuel rod depends on the initial moisture content of the rod and the time lapse between the different stages in the manufacturing process.
It has been found that when the moisture content of the extruded rod is in the relatively high 30% to 40% range, after applying the jacket and overwrap paper to the rod, the moisture in the rod will migrate into the resilient jacket material and the overwrap paper. If that migrated moisture is not removed from the jacket and overwrap, it may cause one or more of several problems to occur, namely, a circumferential enlargement or "swelling" of the overwrapped fuel component, a loosening or failure of the longitudinal adhesive seam of the fuel rod component, or discoloration of the overwrap material. In the event the fuel component enlarges or "swells" circumferentially, downstream processing of the fuel component will be adversely affected.
It has been further found that drying of the extrudate fuel rod to a relatively low moisture content to prevent the aforesaid problems that occur with a high moisture content can also cause problems with processing of the fuel component. For instance, if the overwrapped six-up fuel component has too low a moisture content, i.e., is too dry, the extruded rod tends to fracture or chip when the six-up fuel component is cut into individual fuel elements for assembly into cigarette smoking articles.
It would be desirable therefore to provide a method of and an apparatus for adjusting the moisture content of the carbonaceous fuel element to appropriate levels during assembly of the smoking articles to eliminate the aforementioned problems with fuel components having a moisture content that is either too high or too low at a given stage of processing.